In nonwoven fabrics made of entangled fibers having entangled areas and interconnecting fiber bundles used in various products, such as facings, towels, liners, wipes, and similar applications, there is an inherent weakness in the entangled or "knit" areas where a substantial portion of the fibers is displaced during the entangling action, thus reducing the strength of the fabric. This weakness reduces the reusability and washability of the fabric. It would, therefore, be desirable to form a nonwoven fabric during which provision is made to reinforce these areas, which would serve to provide greater strength and thus durability making wider application of the fabric possible.
It has been known in the art to employ very short, rigid, fusible rods in the entangled or knot areas of an entangled fabric to reinforce the fabric. Short, relatively thick rods of nylon, or the like, have been located in the bud portions, which rods are bonded to the surrounding fibers to strengthen th same. These very short, relatively thick rods (approximately 1/32 inch long, or shorter, of 15 denier material) retain their rod configuration during processing and are not entangled with significant quantities of the surrounding fibers in the bud portin, which minimizes the strength they add to the fabric in the bud area. Additionally, the bulk of the rod adds a hardness to the fabric not present when a relatively short, fusible, bondable fiber capable of being bent is entangled and thus mechanically locked to surrounding fibers in the bud area to strengthen the same.
A patent disclosing a nonwoven fabric employing such short, thick rods in the knot areas and a machine for making same is disclosed in U.S. Pat. No. 3,033,721 granted to F. Kalwaites and assigned to the assignee of the present invention. The patent also claims a nonwoven fabric having fused thermoplastic fibers in the bud areas.
In the present invention, it has been recognized that additional fabric strength in the knot or entangled areas can be obtained if the shorter fibers retained their fiber integrity, and it is to this end that this application is directed. Maintaining the integrity of these fibers maintains the high loft or low bulk characteristics of the finished nonwoven fabric in order to achieve optimum absorption capacity and strength.
Additionally, reference is also made to an application Ser. No. 641,239 filed Aug. 16, 1984, filed concurrently herewith, entitled "An Entangled Nonwoven Fabric Including Conjugate Fibers and the Method of Making Same," in which conjugate fibers are employed and the strength improved by the use of conjugate fibers is obtained. However, the fibers employed in the fabric disclosed in the last-mentioned application are essentially the same length and the conjugate fibers are not concentrated in the knot area to specifically reinforce that portion of the fabric.